Electrochemical cell having a safety vent closure

Abstract

A non-resealable vent closure for galvanic cells, such as nonaqueous oxyhalide cells, which comprises a member force-fitted within a vent orifice and wherein a corrosion-resistant material which is not an integral part of the force-fitted member is disposed between the wall defining the vent orifice and the force-fitted member so as to predictably insure venting after a predetermined gas pressure build-up within the cell.

What is claimed is: 
     
       1. An electrochemical cell in which the active components of the cell are assembled within a housing comprising a container closed at its open end by a cover and having at least one safety vent orifice containing a member force-fitted within the vent orifice to provide a normally fluid-tight seal for said vent orifice, the improvement wherein a material that is corrosion-resistant to the cell's active components and not an integral part of the force-fitted member is disposed at the interface of the wall defining the vent orifice and the member force-fitted within said vent orifice and wherein at least one of said force-fitted member and said corrosion-resistant material is resiliently deformable, such that said force-fitted member is adapted to be at least partially expelled from the vent orifice upon a build-up of a predetermined internal gas pressure inside the cell thereby providing a permanent vent to the atmosphere. 
     
     
       2. The electrochemical cell of claim 1 wherein the force-fitted member is made of a material selected from the group consisting of polytetrafluoroethylene, fluorinated ethylene-propylene polymer, perfluoroalkoxyethylene polymer, ethylene-tetrafluoroethylene polymer, nylon, polypropylene, polycarbonate, acrylic polymers, metals, glass and ceramics. 
     
     
       3. The electrochemical cell of claim 1 wherein the material that is corrosion-resistant to the cell's active components is selected from the group consisting of nylon, polyethylene, polytetrafluoroethylene, fluorinated ethylene-propylene polymer, perfluoroalkoxy polymer, ethylene-fluorinated ethylene polymer, waxes, glasses and metals. 
     
     
       4. The electrochemical cell of claim 3 wherein the material that is corrosion-resistant to the cell's active components is a liner disposed adjacent the wall defining the vent orifice. 
     
     
       5. The electrochemical cell of claim 3 wherein the material that is corrosion-resistant to the cell's active components is a sheet that envelopes a substantial portion of the force-fitted member within the vent orifice. 
     
     
       6. The electrochemical cell of claim 1 wherein a conductive tubular member surrounds the vent orifice. 
     
     
       7. The electrochemical cell of claim 6 wherein a layer of a sealant material is disposed within the conductive tubular member over the force-fitted member in the vent orifice and the area of the housing defining the vent orifice surrounded by the conductive tubular member. 
     
     
       8. The electrochemical cell of claim 7 wherein the sealant material is selected from the group consisting of asphalt, wax, halocarbon wax and epoxy. 
     
     
       9. The electrochemical cell of claim 1 wherein the force-fitted member is coated with a chemically inert material with respect to the cell's components. 
     
     
       10. The electrochemical cell of claim 6 wherein the vent orifice is disposed in the cover and the conductive tubular member is a cylindrical member. 
     
     
       11. The electrochemical cell of claim 1, 6 or 10 which employs a cathode-electrolyte which contains at least one liquid oxyhalide selected from the group consisting of thionyl chloride, sulfuryl chloride, phosphorus oxychloride, thionyl bromide, chromyl chloride, vanadyl tribromide and selenium oxychloride. 
     
     
       12. The electrochemical cell of claim 1 wherein said cell has been manufactured utilizing a method comprising the steps of: (a) placing the solid components of a cell within the container of a cell's housing, said housing comprising the container having secured at its open end a cover and said housing having at least one vent orifice;   (b) feeding the liquid component of the cell through the vent orifice into the housing; and   (c) force-fitting a member and a film or sheet of corrosion-resistant material into the vent orifice in which at least one of said member and said material is resiliently deformable such that the corrosion-resistant material becomes disposed at the interface of the wall defining the vent orifice and the force-fitted member thereby providing a fluid-tight seal at said vent orifice.   
     
     
       13. The electrochemical cell of claim 12 wherein step (d) is added as follows: (d) placing a layer of a sealant over the force-fitted member and the area of the housing defining the vent orifice.   
     
     
       14. The electrochemical cell of claim 12 wherein in step (a) at least one tubular member surrounds at least one vent orifice, and in step (d) the layer of sealant is placed within said tubular member over the force-fitted member in the vent orifice and over the area of the housing defining the vent orifice that is surrounded by the tubular member. 
     
     
       15. The electrochemical cell of claim 1 wherein said cell has been manufactured utilizing a method comprising the steps of: (a) placing the solid components of a cell within the container of a cell's housing, said housing comprising the container having secured at its open end a cover and said housing having at least one vent orifice wherein the wall defining said vent orifice has a liner or coating of a corrosion-resistant material;   (b) feeding the liquid component of the cell through the vent orifice into the housing; and   (c) force-fitting a member into the vent orifice in which at least one of said member and said material is resiliently deformable such that the corrosion-resistant material is disposed between the force-fitted member and the wall defining the orifice thereby providing a fluid-tight seal at said vent orifice.   
     
     
       16. The method of claim 15 wherein step (d) is added as follows: (d) placing a layer of a sealant over the force-fitted member and the area of the housing defining the vent orifice.   
     
     
       17. The method of claim 16 wherein in step (a) at least one tubular member is secured to the housing and surrounds at least one vent orifice, and in step (d) the layer of sealant is placed within said tubular member over the force-fitted member in the vent orifice and over the area of the housing defining the vent orifice that is surrounded by the tubular member.